It is well known in the field of the agricultural machinery to employ a parallel-shaft gearbox to transmit rotational power from the power take-off driveline of an agricultural tractor to the shaft of an auger or screw-conveyor used to convey grain, for example for filling of grain into storage bin. The power take-off driveline couples to an input shaft of the gearbox, which is aligned parallel to the drive shaft of the auger, which carries helical flighting therearound within a surrounding tubular shell so that rotation of the drive shaft causes the flighting to convey granular material disposed between adjacent wraps of the flighting internally along the tube in a predetermined direction, for example to lift the grain from near ground level to the access opening at the top of a grain bin.
Although grain is typically conveyed in the predetermined direction along the auger tube, for example for the bin-filling operation briefly summarized above, it can be desirable to reverse the conveying direction by reversing the rotational direction of the auger shaft, for example for cleaning out the auger for use with a different granular material or in case the auger should become plugged.
The U.S. Patent Application published under Publication No. 2003/0060320 discloses gearboxes for reversing the direction of an auger, but only in a right-angle gearbox configuration in which the input and output shafts of the gearbox are oriented at ninety degrees to one another, and in which the auger is provided with its own dedicated motor. Accordingly, this prior art does not provide a suitable solution for power take-off operation of an auger with a parallel-shaft drive configuration.
It is therefore desirable to provide a gearbox apparatus and operation method suitable to provide direction-reversible output from a power take-off driveline or similar drive source that is operable, or convenient to operate, in only a single predetermined rotational direction.